From the website of
The Ministry of Energy Mines and Petroleum
British Columbia
SURFICIAL PLACERS
“IMPORTANCE: Placer gold deposits account for more than two-thirds of the world's gold reserves and about 25% of known total production in British Columbia. Buried- channel placers have been under developed in British Columbia and other countries because of difficulties in locating deposits and high overburden to ore stripping ratios”
IMPORTANCE: Buried- channel placers have been under developed in British Columbia and other countries because of difficulties in locating deposits and high overburden to ore stripping ratios”“TYPICAL GRADE AND TONNAGE: Deposits are typically high tonnage (0.1 to 100 Mt) but low grade (0.05-0.25 g/t Au, 50-200 g/t Sn). Placer concentrations are highly variable both within and between individual deposits.
ECONOMIC LIMITATIONS: The main economic limitations to mining surficial placer deposits are typically low grades and most deposits occur below the water table. Environmental considerations are also an important limiting factor as these deposits often occur near, or within modern stream courses.”
(Victor M. Levson
British Columbia Geological Survey
Levson, Victor M. (1995): Surficial Placers, in Selected British Columbia Mineral Deposit Profiles, Volume 1 - Metallics and Coal, Lefebure, D.V. and Ray, G.E., Editors, British Columbia Ministry of Energy of Employment and Investment, Open File 1995-20, pages 21-23.)
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